As technologies advance, the specifications of mobile communication technologies are along with upgrade. For example, the transmission technologies are evolved from 2G to 3G or 4G so that the speed of mobile communications may be promoted quickly. However, different mobile communication technologies will operate in different band and mode, such that next-generation communication device with multi-mode and multi-band function is designed and produced by communication device manufacturer so as to meet the market requirement.
Referring to FIG. 1, there is shown a circuit connection diagram of a conventional multi-mode and multi-band front-end device. As shown FIG. 1, the multi-mode and multi-band front-end device 10 comprises an amplifier unit 11, a switching unit 13, a control unit 15 and a wideband matching circuit 17. Wherein the amplifier unit 11 is connected to the switching unit 13 via the wideband matching circuit 17, and the control unit 15 is connected to the amplifier unit 11 and the switching unit 13, respectively.
The switching unit 13 comprises an input end 131 and a plurality of connecting ends 133. Wherein the input end 131 is connected to the amplifier unit 11 via the wideband matching circuit 17, and each of connecting ends 133 is connected to one transmission path 12, respectively. In practical application, an signal amplified by the amplifier unit 11 is transmitted to the input end 131 of the switching unit 13 via the wideband matching circuit 17, and the switching unit 13 is able to selectively transmit the amplified signal to one of the transmission paths 12 according to the frequency band of the amplified signal, such as the control unit 15 controls and switches the switching unit 13.
The wideband matching circuit 17 is usually designed to have characteristics of impedance matching with wide band signals, for example, signals from 2300 MHz to 2700 MHz band, so as to achieve the requirement of the conventional front-end device 10 conforming to multi-mode and multi-band. However, Q (quality factor) of the wideband matching circuit 17 can't be too high in order to achieve the object of wideband operation. Therefore, the transmitted signal passes through wideband matching circuit 17 will have more power loss compared to conventional narrow band matching design. The output power and PAE of the the multi-mode and multi-band front-end device 10 are then degraded due to the wideband matching loss.